(1) Field of the Invention
This invention relates to a new class of hydrocarbon/ethylene oxide random graft copolymers and a process for their preparation.
(2) Description of the Prior Art
Block copolymers, particularly those commonly designated as AB or ABA type polymers, are prepared by creating active sites at either or both ends of a linear backbone polymer and then polymerizing a second monomer at the active site(s). The product is a linear polymer containing one block of the backbone polymer (B) terminally joined to one or two blocks of the second polymer (A). The linkage by which the blocks are joined depends on the active site employed and the function by which it was attached to the backbone polymer. The strength or weakness of this linkage may control the thermal and chemical stability of the block copolymer.
Graft copolymers differ from block copolymers in that they are never linear, having a minimum of one branched chain per molecule. The graft chains are randomly arranged on the base polymer. One or two of the grafts may be terminally attached, but it is not essential that any of the grafts be attached to an end of the base polymer. The essential feature is the necessarily branched structure which accounts for some of the essential physical properties of the graft copolymer.
Dutch Pat. No. 7,308,061 (1973) shows the preparation of block copolymers (ABA) of diene polymers (B) and polyalkylene oxide (A) by polymerizing a diene hydrocarbon with a difunctional organopotassium compound and polymerizing an epoxyalkane onto the ends of the diene polymer. The products are agents for improving antistatic properties and impact resistance of synthetic resins, coatings for fibrous fleeces, components of adhesives and protective colloids.
Japanese Pat. No. 71 34,984 (1971) shows the preparation of block copolymers by heating hydroxyl-terminated polybutadiene with potassium hydroxide and ethylene oxide to give a butadiene/ethylene oxide graft copolymer.
U.S. Pat. No. 3,175,997 (1965) shows the preparation of polymers with terminal hydroxyl groups by polymerizing monomers with an organoalkali metal catalyst followed by reaction with an epoxide such as ethylene oxide.
Block-graft copolymers are shown in U.S. Pat. No. 3,821,331 in which terminal blocks and random side chains of pivalolactone polymer are attached through ##STR1## linkages to a diene back-bone polymer.
In U.S. Pat. No. 3,897,513 graft copolymers are prepared by contacting an amorphous base polymer having random anionic sites selected from the group consisting of allylic, benzylic and aromatic carbonions, carboxylic anions and alkoxide anions with a .beta.-lactone. Carbonion sites are developed by reacting the base polymer with an alkyllithium-diamine complex thereby lithiating the base polymer.